A type of bacteria that causes what is commonly called a Staph infection and can potentially cause a life-threatening illness should it infect a major organ. Staphylococcus is responsible for approximately 34% of all SSI. 20% by coagulase positive Staph and 14% by coagulase negative Staph. S. epidermitis, a skin resident in high numbers on almost everyone, is coagulase negative. S. aureus is a more virulent (aggressive) pathogen; present on a larger percentage of people (on the skin and in the nares) is coagulase positive. Many Staph infections respond to antibiotics; however, there are increasing numbers and types of resistant strains emerging (e.g. MRSA, VISA, VRSA): – MSSA Methicillin sensitive S. aureus – MRSA Methicillin resistant S. aureus – VISA Vancomycin intermediate S. aureus – VRSA Vancomycin resistant S. aureus Approximately 50-60% of S. aureus infections in the US are MRSA. Percentages vary dramatically in different countries.